Margelo

Builds and designs React Native Nitro Modules with Nitrogen, HybridObject TypeScript specs, generated native implementations, zero-copy and native-state APIs, Swift/Kotlin/C++ bindings, example apps, and testing. Use when creating a Nitro Module, adding or reviewing HybridObjects, designing Nitro-specific public APIs, implementing native functionality, or setting up the nitrogen codegen pipeline. Pair with api-design for general library API shape.

Design and review predictable public APIs for TypeScript, JavaScript, React, and React Native libraries. Use when shaping exported functions, classes, hooks, options objects, event and listener APIs, error behavior, naming, cross-platform abstractions, or JS-only packages. Pair with build-nitro-modules when the library is backed by Nitro.

Best-practices guide for react-native-vision-camera v5 (Nitro rewrite, April 2026) and migrating from v4. Use when installing, configuring, or writing code with the Camera, outputs, frame processors, recording, or barcode/depth/RAW features. Also use when converting v4 code (photo={true}, takePhoto, useCameraFormat, useFrameProcessor) to the new v5 API.

Analyzes .swift files for thread safety, async/await patterns, and Apple framework usage. Flags race conditions and suggests safer actor-based refactors.

Swaps AsyncStorage for MMKV—a faster, encrypted key-value store that integrates with zustand, redux, and other state managers. Includes migration patterns and multi-process setup.